In order to improve the surface appearance of panels most often based on wood, it is conventional to use so-called laminated or high performance laminated boards or sheets as a function of the setting, called decorative laminates. In a known manner, such decorative laminates are present in the form of a board which generally has a part called the core, formed by an assembly of superposed layers or sheets made out of cellulose fiber material, and most often out of kraft paper, joined on one of its large surfaces with a decorative layer, most often in the form of a decorated paper. The layer(s) constituting the decorative layer(s) has (have) colors or decorative patterns, and is (are) impregnated with melamine resins and/or is (are) covered with a surface covering impregnated with phenolic resins. The different elements constituting these decorative laminates are connected together by a so-called “high pressure” process which is described below. The opposite side of the board from the decorative layer is most often capable of being glued on a support.
It is common to put a surface covering on the decorative paper, ensuring its protection. This surface covering most often consists of a so-called “overlay” sheet of paper made of alpha cellulose fibers impregnated with a thermosetting melamine-formaldehyde resin making it possible to produce a transparent protective covering after thermocompression.
Such decorative laminates are described, for example, in the documents U.S. Pat. No. 3,616,021 or FR 2 267 206 in the name of the Formica company, which can be referred to for more details.
These types of decorative laminates are rather rigid and cannot be shaped at room temperature. Such laminates are prepared according to a discontinuous pressing process at high pressure and generally have a thickness between 0.5 and 1 mm. The high pressure process consists of the simultaneous application of heat (temperature ≧120° C.) and a determined high pressure (≧5 MPa), in order to allow flow, and then polycondensation of the thermosetting resins so as to obtain a non-porous homogeneous material (with a density ≧1.35 g/cm3), whose surface has the required appearance.
Another line of decorative laminates, in this case prepared according to a continuous pressing process at a lower pressure, has been developed. The decorative laminates obtained by such a process are thinner (most often with a thickness of 0.25-0.6 mm) and more flexible, but their surface resistance, particularly with regard to external stresses and chemical products, has poorer performance.